2010/01/01 by Maarten Oelering.

Why I chose a commercial grade MTA

For sending emails, there is a wealth of solutions. On the open source side, there is Sendmail, Qmail, Exim and Postfix. Then there are a number of commercial MTAs available, at different price levels. The most well known vendors are Message Systems, Port25 and StrongMail.

Postfix is a popular open source MTA thanks to it’s security and performance. I myself have used it in the early 2000s to power an email service provider. At one time I had 8 servers sending up to one million emails per day.

However, Postfix has a fundamental problem, just like the other open source MTAs. They have a design focus on filtering and distributing inbound email. That means they are very good at accepting mail from different sources and delivering them locally. Delivering large volumes of email requires another design approach.

If you are a sender concerned about deliverability you will notice that it is important to sign email with DKIM, segment mail streams over different IPs, and adapt delivery to reputation related errors. Commercial MTAs targeted for outbound delivery make these things a lot easier. They support many IPs, parallel queues and provide lots of delivery related configuration options.

Around 2004 I decided to switch from Postfix to PowerMTA from Port25. A redundant set of two servers was enough to replace the 8 Postfix servers. Still it was quite an investment, but it was all paid back in less administration and better quality. Instead of troubleshooting performance issues I could concentrate on other things, like deliverability management.

After I started to work as a consultant in 2007, I have also worked with StrongMail and Message Systems. These are also good products, each with distinctive advantages. What I like about PowerMTA is that it does one thing, and does it well, making it a manageable product with a great price/value ratio.

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